FIG. 3.
Replication of FR/8xRep* plasmids are dependent on EBNA1. BJAB and BJAB/EBNA1 cells were transfected with FR/8xRep* plasmids as indicated. At 4 and 6 days posttransfection, plasmids were isolated from 1.5 × 107 cells. For Southern blotting, 90% of each sample was digested with DpnI and MluI, and 10% was digested with MluI only as indicated at the top. To monitor the recovery of plasmids and the completeness of DpnI digestion, the pPUR backbone plasmid was used as the “spiked plasmid” DNA. The percentages of replicated DNA refer to the ratio of the level of DpnI-resistant plasmid over the level of MluI-linearized plasmid. The numbers were normalized against the level of the spiked DNA in each sample and are indicated below the blot.